Electrode for vapor electric apparatus.



G. A. KRAUS & R. D. MAILEY.

ELECTRODE FOR VAPOR ELECTRIC APPARATUS.

APPLICATION FILED JUNE 30. 1910.

1,109,764. Patented Sent. 8, 1914;.

55 anode the check valve action is liable to be NI'IEI) STATES PATENT OFFICE.

massacn'lusn cnmns A. KBAUS, or NEWTON HIGHLANDS, Ann ROY n. MAILEY, or LYNN,

ELECTRODE FOR YAPOR ELECTRIC APPARATUS.

Specification of Letters mint.

Patented Sept. 8, 1914.

Application filed June30, 1910. semi in. 569,898.

To all who/a it may concern:

Be it known that we, CHARLES'A. KnAU's! and ROY D. iVIAILnr, both citizens of the United States, and residents, respectively, of Newton Highlands and Lynn, in the counties of Middlesex and Essex and State of Massachusetts, have invented new and useful Improvements in Electrodes for Vapor Electric Apparatus, of which the following is a specification.

Our invention'relates to the construction of vapor electric apparatus, and has for its object improved control over the temperature of an anode in such apparatus. ,Heretofore it has been customary in the operaticnjof such vapor electric apparatus as mercury arc rectifier-s, either to allow an anode to become heated to a definite ,tem-' perature depending upon the amound of energy expended on the anode surface, or to cool the anode as by means of heat radiating or conveying devices. Sofar as we are informed, the mercury arc rectifiers commercially constructed and used have been such as to operate Without temperature control of the anode which has been allowed to attain whatever temperature the operation of the apparatus produced. This practice is disadvantageous because the elevated temperature tends to drive gases out of the metallic body of the electrode and also since at high temperatures the anodes are less efiective in their check valve action on the electric current. Moreover, at high temperatures the tendency of the anode to disintegrate is considerably greater than it is at low temperatures. In the construction of rectifiers of small current capacity, for. example, as high as 50 amperes, these difiiculties are not serious. But when a rectifier is designed to carry, currents from 500 to 1000 amperes, the disadvantage in allowing the anode to rise in temperature with no control except their own condition and radiation becomes very serious. It is not sufiicient simply to coolthe-anode by' some external means. If: the temperature of the anode and its 'lflid is made to -f all too low, there is a tendency for mercury to condense upon it. 'The :checkwalve action of an anode in the rectification of analternating current is largely dependent upon the solid state of its surface and upon low vapor pressure. If mercury condenses upon the limrts.

interrupted and short-circuit arcing results in the rectifier which 'not alone interrupt-s its normal operation, but also subjects the apparatus to possible injury. The temperature at which mercury condenses on the anode and anode leads of'course de ends upon the details of design and the conditions under which the apparatus is operating.

The temperature of the mercury of which the cathode is composed may rise as high as 200 0., but in any case the temperature must be -below 360. C. which is the normal boiling point ofmercury; On the other hand, the anode temperature should be kept as low as is consistent with the prevention of condcnsation'of mercury upon its surface.

Therefore, a te perature higher than-360 C. is of, no advantage. The control of anode temperature above 200 C. by means of circulation of liquid is diflicult to accomplish, especially in {view oi the fact that the amount of heat liberated atthe anode is 'proportional to the current passing through it, and will [therefore vary within wide Byour invfention hereindescribed means are provided whereby theanode isa mercury arc rectifier or analogous apparatusmay be maintained at substantially constant temperature which lies Within the upper and lower safe limits of range.

We employ for. an anode the lower lLlOD yOf .a closed metal tube, of which the closed end constitutes a -receptacle for a suitable liquid; from this receptacle; the tube extends to the upper part of the container of the apparatus, preferably the cover or top thereof. The'liquid chamber and upwardly reaching tubular extension are both of metal, and are preferably in one integral; piece, or made substantially integral I by Welding. The boilin .pointoi-the liquid in the, hollow receptac e should be in the neighborhood of 360 centigrade. It must be capableofprolonged use without chemi cal change and should be liquid at ordinary temperature. While other. liquids may doubtless be employed, it is obvious from the foregoing is adapted to our pur ose. Since it is a metal, ,the distribution 0 heat through itsentire at mercury is -,peculiarly body takes place rapidly; condensed vap r of such aliquid returns/to the liquid body readily because of its high specific gravity and it does-not form a filmc'f non-conduc- .illustrated an example of our invention, in

tire material over the condensing surface as do other liquids which are higher in thermal insulating quality and which would wet the condensing surface.

Close attention should be paid to the details of construction of an anode of which the temperature is to be controlled by a body of liquid. For example: Allowing six volts for the potential drop at the anode surface the energy expended at the anode and which must be removed by the vaporization and recondensing of the liquid within the anode, amounts to 2250 joules per second for a rectified current of 750 amperes. This is approximately 500 small calories per second. Assuming the heat of vaporization to be that of mercury or calories, the amount of liquid evaporated in the anode must amount approximately to 9 grams per second or half a kilogram per minute. With so high a rate of evolution per minute, the hollow anode which contains the mercury must be adequately strong in order to withstand the mechanical shock sustained in the course of the boiling of the mercury or such other liquid as may be employed. In any case the size of the boiling receptacle which is to act as an anode must be large enough to permit the liquid to boil readily. We recommend that an area of one square inch of anode surface be allowed for every 150 amperes of maximum rectified current.

The container E is a closed vessel into which the electrode leads are sealed by insulating joints. The main anode is represented at A, an auxiliary anode at A, a cathode lead at K, and the mercury cathode at M, contained in an insulating cup or vessel .V.

In the drawings hereto annexed there is which E represents a portion of a metallic rectifier container, from which the anode A is suspended. The structure of which the anode proper (that is to say, the conductive.

surface from which the arc proceeds) forms a part, consists of a hollow cylindrical bulb B, preferably of steel which is integral with, or welded to, a tubular extension D. The tube D is preferably slightly smaller in diameter than the bulb B, It extends from the anode bulb B to' the top of the apparatus, where-it is joined to the container E by means of an insulating gas tight joint at F. Insidethe tubular riser D there "is suspended a double tube G'through which. a circulation of cooling fluid, preferably water, may be -maintained.- The"-tubular riser D may be used as the anode lead, and will preferably be so used, though an inner member, such as the double tubeG, if continued downward or joined to the side of the bulb B, may be used as the electrical lead or anode connection.

The pool of liquid C, in the anode bulb. determines the maximum temperature of the anode A by boiling; its vapors rise in the extension D and are condensed therein, and return to the. pool C. The joint at F, being remote from the seat of agitation and ebullition, is not affected thereby. The temperature of the tubular extension D decreases as the point of suspension is approached, so that at the joint F the temperature of the tube D, and its rate of change of temperature are such-that the joint is not endangered thereby.

The greater the current through the anode, the higher will be the temperature along the tube D, which, being wholly within the container will have a higher temperature at all points than the portions of the container at the same levels, so that mercury will condense in the container walls and not in the tube D.

What we claim and desire to secure by Letters Patent is:

'1. In a vapor electric apparatus, a closed container, an anode and a metallic extension together forming a chamber, an insulating seal securing the extension to and insulating it from the container, a pool of liquid in the bottom of the chamber, and means between the anode and the seal to condense the vapors of the liquid within the chamber and return the condensed liquid to the pool. 2. In a vapor electric apparatus, a closed container, an anode and a metallic extension together forming a chamber within the container, a pool of' liquid in the bottom of the chamber, means to condense vapor of the said liquid and return the condensed liquid to the pool, and an insulating seal without the region of condensation of said vapor, joining the extension to the container.

3. In a vapor electric apparatus, a closed container, an anode and an extension together forming a chamber within the container, the lower portion of said chamber being in enlarged bulbform, a pool of liquid in the bottom of the bulb, and aninsulating seal securing the extension to the container wall above the region of condensation of vapor from the said liquid.

Signed by us at 'Boston, Massachusetts,

this twentieth day of June, 1910.

' CHARLES A. KRAUS.

ROY D. MAILEY.

\Vitnesses:

CHARLES D. VVoonBnRRY,

JOSEPHINE H. RYAN. 

